Three open cases stemming from the ATF's "Operation Fast and Furious" will be transferred from the U.S. Attorney's Office in Arizona to Los Angeles and San Diego, officials said Tuesday.

The move was requested by the U.S. Attorney's Office out of an "abundance of caution and in the best interest of these prosecutions," agency spokesman Manny Tarango said in an emailed statement.

Sen. Charles Grassley, R-Iowa, and Rep. Darrell Issa, R-Calif., have urged the Justice Department to transfer the cases.

The move is "clearly in the best interest of achieving just outcomes and removes the apparent conflict of interest that Arizona prosecutors had in bringing cases from an operation they mishandled," said Issa in an emailed statement.

The move is the latest fallout from congressional inquiries into the ATF operation. Last week, U.S. Attorney Dennis Burke resigned and Assistant U.S. Attorney Emory Hurley, who was responsible for the day-to-day operations of Fast and Furious, was reassigned to the civil division at his own request. Before that, William Newell, former head of the Phoenix ATF Office, also was reassigned.